Tropentag, October 5 - 7, 2011 in Bonn "Development on the margin"

Effects of Mycorrhiza and Plant Growth Promoting Rhizo-bacteria Inoculants on Rice Crops in Northern India

¹G.B. Pant University of Agriculture and Technology, Dept. of Biological Sciences, India
²Research Institute of Organic Agriculture (FiBL), Soil Sciences Division, Switzerland
³The Energy and Resources Institute, Biotechnology and Bioresources Division, India
⁴f. Agroscope Reckenholz-Tänikon Research Station (ART), Switzerland

Abstract

Mutualistic root microorganisms such as arbuscular mycorrhizal fungi (AMF) and plant growth promoting rhizo-bacteria (PGPR) can ameliorate plant nutrition through an extended extra-radical hyphal network and by nutrient mobilisation. Running under the Indo-Swiss Collaboration in Biotechnology (ISCB), our project focuses on the integration of AMF and PGPR as bio-fertilisers in wheat-rice and wheat-black gram systems.

The inoculants were isolated and selected from wheat roots. AMF inoculation was performed with a natural consortium (Mnat) multiplied via host plants and comprising several AMF strains. In addition, two AMF single strains multiplied via a root organ culture were applied (an AMF strain isolated from Mnat and a commercial strain). The PGPR inoculum (Ps) consisted of two fluorescent Pseudomonas strains.

Effects of inoculants, presented here on rice crops (Oryza sativa [L.]), were assessed between 2006 and 2009 in a trial at Bhawanipur, Uttar Pradesh. The plots were managed at fertiliser level Zero (3 t ha^-1 farmyard manure) and Farmer's Practice (FYM + mineral fertilisers), in the presence or absence of a Sesbania green manure intercrop before rice. Calculated across both fertiliser levels and over four years, rice grain yield was most increased by application of the dual inoculum “Mnat+Ps”. Compared to the un-inoculated treatment, the yield was 22 % higher without and 30 % higher with Sesbania. This corresponds to an increase from 2.64 t ha^-1 to 3.21 t ha^-1 grain dry matter yield without Sesbania, and from 2.99 t ha^-1 to 3.88 t ha^-1 grain DM yield with Sesbania (means of four rice crops, p ≤ 0.001). AMF single strains were less effective than Mnat. Phosphorus, zinc and iron concentration in rice grain was significantly increased in all inoculation treatments. The inoculants were effective both at Zero and Farmer's Practice fertiliser level.

Our results show that the bio-fertilisers tested have the ability to optimise rice crops in a wheat-rice rotation in India. Applying the same inoculants, Mäder et al. (Soil Biology & Biochemistry 43, 2011) obtained a wheat grain yield enhancement of 41 % compared to un-inoculated plots, suggesting that isolates from the rhizosphere of the target crop can even be more efficient.

Keywords: Inoculation, micro-elements, microorganisms, mineral nutrient concentration, mycorrhiza, PGPR, Pseudomonas, rice, Sesbania, yield

Contact Address: Estelle Berset, Research Institute of Organic Agriculture (FiBL), Soil Sciences Division, Ackerstrasse, 5070 Frick, Switzerland, e-mail: estelle.bersetfibl.org